JP2001224553A - Imaging instrument for capusle endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized imaging instrument for capsule endoscope with small power consumption. SOLUTION: This imaging device for capsule endoscope comprises a lighting means for lighting a subject part within a body cavity, an image sensor having a photoelectric converting means for photoelectrically converting the subject light to a signal charge and accumulating it and a scanning means for scanning and reading the accumulated signal charge, which outputs the image signal read by the scanning means, a signal processing means for processing the image signal, a transmitting means for wirelessly transmitting the signal charge accumulated by the image sensor as image signal, and a power supplying means for supplying power, all of which means are provided within a sealed capsule. The device alternately repeats a lighting cycle of setting the power supply at least to the lighting means ON to accumulate the signal charge in the image sensor; and a transmitting cycle of setting the power supply to at least the scanning means of the image sensor, the signal processing means and the transmitting means ON to transmit the image signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus for a capsule endoscope which is introduced into a body to image a body cavity and wirelessly transmits the image outside the body.

[0002]

2. Description of the Related Art As a means for observing a body lumen, a conventional endoscope connected to an external device through a long flexible tube is used to reduce the pain of a subject. A capsule endoscope that can be used without being connected to a computer has been proposed. The capsule endoscope allows a subject to swallow a capsule endoscope including an image pickup device such as an image sensor and a transmitter, and wirelessly transmits an image of the subject from within a body cavity. This capsule endoscope advances in the body cavity of the subject by the subject's gastrointestinal peristalsis, and its speed is several meters per minute.
Since it is about m, it takes several tens of hours from the time of swallowing until the end of the test to be released outside the body.

In order to supply sufficient electric power to drive the capsule endoscope for several tens of hours, the size of a built-in battery increases, and the capsule endoscope cannot be downsized. If the battery is made small, it is impossible to observe the lower digestive tract, which takes a long time after swallowing.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a small-sized capsule endoscope imaging apparatus which consumes less power, based on the above-mentioned problems of the capsule endoscope.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the fact that the speed at which a capsule endoscope moves through a body cavity by peristalsis is extremely slow, and it is sufficient to observe not only moving images but also still images. That is, the imaging device for a capsule endoscope according to the present invention includes: an illuminating unit that illuminates a target portion in a body cavity; an imaging unit that captures an image of the target portion and outputs an image signal; and a transmission that wirelessly transmits the image signal. Means for supplying power to the lighting means, and a power supply means for supplying power to the lighting means for turning on the power supply to at least the lighting means to accumulate signal charges in the imaging means; and at least the imaging means and transmission. And a transmission cycle for transmitting the image signal by turning on the power supply to the means. The imaging means includes a photoelectric conversion means for photoelectrically converting subject light into signal charges and accumulating the same, a scanning means for scanning and reading the accumulated signal charges, and an image sensor for outputting an image signal read by the scanning means;
Signal processing means for processing the image signal.

In this imaging device for a capsule endoscope,
According to the illuminance of the object by the illuminating means, the illumination cycle is a time during which signal charges for one field or one frame can be accumulated, and the transmission cycle is to read image signals for one field or one frame. It is preferable that the transmission time is set. It is practical to execute the illumination cycle and the transmission cycle once every second.

The lighting means is a light emitting diode, and when a power is supplied to the transmitting means, a reverse voltage is applied to turn off the light. When no power is supplied to the transmitting means, a forward voltage is applied. By arranging the lighting means, it is easy to reduce the power consumed by the lighting means. Alternatively, a power supply switching unit for the scanning unit, the signal processing unit, the transmission unit, and the illumination unit may be provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. As shown in FIG. 4, the capsule endoscope 80 in which the imaging device 10 is housed in a sealed capsule is swallowed by a subject and introduced into a body cavity. The introduced capsule endoscope 80 is
An image of the body cavity surface (the part to be inspected) illuminated by the LED 40 as the illumination means is formed by the imaging optical system L, captured by the image sensor 21, and transmitted wirelessly from the transmission antenna 62.

FIG. 1 shows a block diagram of an image pickup apparatus 10 that performs this image pickup and transmission. The imaging device 10 includes a substrate 12 on which the image sensor unit 20 and the LED 40 are mounted, and a substrate 14 on which the modulation unit 50 and the transmission unit 60 are mounted.
The image sensor unit 20 includes an image sensor 21 and a video signal generation circuit 30. Image sensor 21
Are horizontal and vertical shift registers (scanning means) 22H, 2
2 V and an image area (photoelectric conversion means) 23, subject light is photoelectrically converted in the image area 23 to accumulate signal charges, and the signal charges are transferred to the shift registers 22H and 22V.
And outputs the image signal as an image signal. The video signal generation circuit 30 includes a sample / hold circuit (S / H) 31, an A / D converter 32, a video processor 33, and an encoder. The image signal output from the image sensor 21 is held by a sample-and-hold circuit 31 and is stored in an A / D converter 32.
The video signal is processed by the video processor 33 and the video signal is processed by the video processor 33.

The substrate 12 further sequentially outputs a drive signal (scanning readout signal) for driving the image sensor unit 20 based on the signal output from the first oscillator 42, the inverter 44, and the first oscillator 42, a synchronization signal, and the like. A timing generator (TG) 46 is provided. The inverter 44 turns on and off the power of the modulation unit 50 and the transmission unit 60 in response to the signal of the timing generator 46, and the LED provided on the substrate 12
40 turns off / on. When the power of the modulation unit 50 and the transmission unit 60 is on, the LED 40 is not lit because a reverse voltage is applied to the LED 40 (transmission cycle), and when the modulation unit 50 and the transmission unit 60 are off, the forward voltage is applied to the LED 40 and lit. Yes (lighting cycle). That is, when one of the LED 40 or the modulator 50 and the transmitter 60 is turned on, the other is turned off.

The modulator 50 of the substrate 14 includes a modulator 51, a second oscillator 52 for outputting a carrier signal, and a multiplier 53. The output of the encoder 34 is input to the modulator 51, and the modulated signal and the carrier signal of the second oscillator 52 are multiplied by a multiplier 53. The transmitting unit 60 of the substrate 14 includes a transmitter 61 and a transmitting antenna 62, and transmits a signal from the modulator 50 to the transmitting antenna 6 via the transmitter 61.
Call from 2.

FIG. 2 is a circuit diagram of a power switch for turning on and off the power supply of the battery 70 of the capsule endoscope. Since the switching is performed in a non-contact manner by the reed switch 71 which opens when it is placed in a magnetic field, the capsule endoscope is kept watertight. In addition, for example, during transportation or when not in use, if the capsule endoscope is stored in a packing box or storage case provided with a magnet, the power can be turned off. When the reed switch 71 is turned on and power is supplied, the timing generator 46 causes the imaging device 10 to operate sequentially in a predetermined cycle.

FIG. 3 shows a time chart for switching between the illumination cycle and the transmission cycle. The illumination cycle and the transmission cycle are switched by a synchronization signal transmitted from the timing generator 46 that has received the basic clock from the first oscillator 42. In the lighting cycle (during light accumulation), the LED 40
Illuminating light is emitted, and signal charges are accumulated in the image sensor 21. During this time, the modulation unit 50 and the transmission unit 60 do not consume power because the power is off. In the transmission cycle (during image read transmission), a video signal output from the image sensor 21 and generated by the video signal generation circuit 30 is transmitted to the modulation unit 50. The video signal is modulated by the modulator 50 and transmitted from the transmitting antenna 62 via the transmitter 61. During this transmission cycle, the LED 40 does not light.

A calculation example for determining the illumination cycle (light accumulation time t1) and the transmission cycle (transmission time t2) in the present embodiment will be described below. 1) Conditions Illumination light: LED Luminous intensity (assumed to be a point light source): 3 [mcd] (M.
S. C. P) Distance from illumination light to subject: 10 [mm] Image sensor Sensitivity of image sensor: 15 [lx] (F1.2) (for light accumulation time of 1/60 second) Aperture value of imaging optical system: F8 field Frequency f _v = 60 Hz 2) Calculation of light accumulation time Since illuminance = luminance / distance ² , illuminance of the subject is illuminance = 3 × 10 ⁻³ / (10 × 10 ⁻³ ) ² = 30 [lx] From the above conditions, the amount of light incident on the image sensor is 0.3
[Lx], the normally required incident light amount 15
With respect to [lx], if 15 / 0.3 = 50, and if the accumulation time is about 50 times, imaging (accumulation of signal charges) by appropriate exposure can be performed. Since the field frequency is 60 Hz, the scanning time per field (16.7 ms)
A sufficient light amount (signal charge) can be obtained with a light accumulation time of 50 times, ie, t1 = 16.7 [ms] × 50 = 833 [ms]. 3) Calculation of transmission time If the pixel configuration of the image area 23 is 200 pixels × 200 pixels, all the pixels are 40 k pixels, and the data amount after digital conversion (8-bit decomposition) of the signal charges accumulated in each pixel is 320 kbit. . Set the transmission rate to 14 [Mbit
/ S], t2 = 320 [kbit] / 14 [Mbit / s] = about
The transmission is completed in 22.3 [ms]. 4) Configuration time of one screen From the above, the time required to accumulate and transmit the pixel signals for one screen is t1 + t2 = 833 [ms] +22.3 [ms] = 855.3 [ms] . In view of design, it is desirable that the configuration time of one screen is 1 s.

According to the above calculation example, if light accumulation and transmission are performed at a cycle of one second, the movement of the capsule due to peristaltic motion in the body cavity is about several mm per minute, so that the image is sufficiently observed without a large leap. Is possible.

In this embodiment, the cycle is set to one second due to various conditions. However, the present invention is not limited to the above calculation example. For example, when the image sensor 21 having a different number of pixels is used, the transmission cycle is lengthened according to the number of pixels. Alternatively, when the LED 40 is shortened or has different luminous intensity, it can be implemented by adjusting the illumination cycle. It is also possible to provide a power-off cycle between the illumination cycle and the transmission cycle, or to execute an illumination cycle with a plurality of different illumination times or light intensities (auto bracketing).

[0017]

As described above, according to the imaging apparatus for a capsule endoscope of the present invention, the accumulation time of the signal charge is lengthened to make the illumination dark, and the power is supplied alternately to the respective parts, thereby consuming power. Since the power can be reduced, the size of the battery can be reduced, and a small-sized capsule endoscope that can be driven for a long time can be realized. Further, since the illumination lamp is dark and no problem occurs due to heat generation, a capsule endoscope safe for a human body can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a circuit configuration of an imaging device for an endoscope according to the present invention.

FIG. 2 is a circuit diagram showing a power switch portion of the imaging device of the capsule endoscope.

FIG. 3 is a time chart showing switching between an illumination cycle and a transmission cycle.

FIG. 4 is a sectional view showing a capsule endoscope to which the present invention is applied.

[Explanation of symbols]

 Reference Signs List 10 imaging device 12 14 substrate 20 image sensor section 21 image sensor 22H horizontal shift register (scanning means) 22V vertical shift register 23 image area (photoelectric conversion means) 30 video signal generation circuit 31 sample hold circuit (S / H) 32 A / D converter 33 Video processor 34 Encoder 40 LED 42 First oscillator 44 Inverter 46 Timing generator (TG) 50 Modulator 51 Modulator 52 Second oscillator 53 Multiplier 60 Transmitter 61 Transmitter 62 Transmit antenna 70 Battery 71 Reed switch 80 Capsule Endoscope L Imaging optical system t1 Light accumulation time t2 Transmission time

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiro Ninomiya 2-36-9 Maenocho, Itabashi-ku, Tokyo Inside Asahiko Gaku Kogyo Co., Ltd. (72) Inventor Tetsuya Nakamura 2-36-9 Maenocho, Itabashi-ku, Tokyo No. Asahi Kogaku Kogyo Co., Ltd. (72) Inventor Masahiro Fushimi 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd. (72) Masaru Eguchi 2-36-9 Maenocho, Itabashi-ku, Tokyo No. Asahi Gaku Kogyo Co., Ltd. (72) Inventor Kenichi Ohara 2-36-9 Maeno-cho, Itabashi-ku, Tokyo F-term in Asahi Gaku Kogyo Co., Ltd. 4C061 BB01 CC06 DD10 GG22 JJ06 PP04 QQ06 RR03 UU06

Claims (6)

[Claims] 1. Illumination means for illuminating a test portion in a body cavity;
An imaging unit for imaging a portion to be inspected and outputting an image signal; a transmission unit for wirelessly transmitting the image signal; and a power supply unit for supplying electric power in a sealed capsule; and supplying power to at least the illumination unit. And a transmission cycle for turning on the power supply to at least the imaging unit and the transmission unit to transmit the image signal. Imaging device for capsule endoscope. 2. Illumination means for illuminating a subject in a body cavity;
Photoelectric conversion means for photoelectrically converting subject light into signal charges and accumulating; scanning means for scanning and reading the accumulated signal charges; and an image sensor for outputting an image signal read by the scanning means; and processing the image signal A signal processing unit; a transmitting unit for wirelessly transmitting the signal charges accumulated by the image sensor as an image signal; and a power supply unit for supplying electric power, in a sealed capsule, and turning on power supply to at least the illumination unit. An illumination cycle for turning off the power supply to the scanning unit, the signal processing unit, and the transmitting unit of the image sensor to accumulate signal charges in the image sensor; and at least the scanning unit, the signal processing unit, and the transmitting unit of the image sensor. The power supply to the lighting unit is turned on, the power supply to the lighting unit is turned off, and the image signal is transmitted. An imaging device for a capsule endoscope, wherein a transmission cycle and a transmission cycle are alternately repeated. 3. The imaging device for a capsule endoscope according to claim 1, wherein the lighting cycle corresponds to one field or one frame of signal charges corresponding to a subject illuminance at a predetermined distance by the lighting means. An imaging apparatus for a capsule endoscope, wherein the exposure time is a proper exposure time that can be accumulated, and the transmission cycle is a time during which an image signal for one field or one frame can be read and transmitted. 4. The capsule endoscope imaging apparatus according to claim 1, wherein the illumination cycle and the transmission cycle are executed once per second. 5. The imaging apparatus for a capsule endoscope according to claim 1, wherein the illumination means is a light emitting diode, and a reverse voltage is applied when power is supplied to the transmission means. An imaging device for a capsule endoscope, which is arranged to be turned off and to be turned on by applying a forward voltage when power is not supplied to a transmission unit. 6. The capsule endoscope imaging apparatus according to claim 1, further comprising a switching unit for switching power supply to the scanning unit, the signal processing unit, the transmission unit, and the illumination unit. Endoscope imaging device.